We've got the Vargas Stage2 N55 turbo running on our 2011 135i DCT car and was finally able to hit up the dyno for a little tuning today. The vehicle is FBO but equipped with a CPE replacement catted DP. We've recently modified both the E series N55 ISO JB4 firmware for large turbo support and developed an entirely new back end flash. To enable the JB4 large turbo maps you just enable the 3.5 bar TMAP sensor using version 5.5 or later.

This changes map 1 to 16psi, map 2 to 19psi, and methanol mapping as high as your turbo will take you. All with reduced taper to redline to let the larger turbo shine.

Dyno testing was done on simulated 93 octane (91 + 1 can of NOS octane booster), and the methanol testing was done with a single CM10 nozzle. Overall very pleased with the results especially for an odor free vehicle. The pump map is a touch aggressive but really showcases what the turbo can do. On pump gas I think the car would come very close if not take our F80 M3 if the M3 is running the stock tuning. And on meth would come very close to the M3 on the E30 map.

Terry now that you've been able to push N55s a bit, i'm curious as to what your overall thoughts are on that motor relative to the 54. We always speculate about bottom end strength and all that jazz, but it's never really gotten beyond speculation.

It's a broad question but what do you think of the 55 as a tuning platform?

Terry now that you've been able to push N55s a bit, i'm curious as to what your overall thoughts are on that motor relative to the 54. We always speculate about bottom end strength and all that jazz, but it's never really gotten beyond speculation.

It's a broad question but what do you think of the 55 as a tuning platform?

It sure as hell seems octane hungry based on those deltas.

On the N55 as a higher HP motor, who knows. I've not torn one down yet other than the top end for VANOS repairs. On the short block I presume it's using the same cast pistons the N54 uses and that as long as its tuned safely should be OK for 550-600whp. We've been running it at 475whp on DrN55 for some time without issue. The combustion chamber on this motor is really tight MBT is much lower than you'd think. Around 5-6 degrees when running 20psi+ on a larger turbo. The OEM timing curve of 6-8 degrees is about perfect for the OEM turbo with higher octane as well.

Why did you stop at 6400rpm?
Do you need the 3.5bar sensor if you are only going to 20/21psi?
Also interesting that you have settled on 6 degrees of timing rather than the 9 you were previously running.

The turbo stops making power over 6500rpm so I just stopped revving it up. We shift it around 6000rpm.

On the timing I found 6 degrees to be a pretty good MBT value for it. From 6-11 in 1 degree increments there is basically no gain all else being equal. Dropping below 6 started to drop power a bit. The pump map I ran on the same curve which produced the best figures but a curve of around 5 degrees would be more appropriate. We are evaluating using the same curve with a little less aggressive boost curve. Because it will simplify things for the end users if the same back end flash can be optimized for both on and off meth, allowing on the fly map changes where the JB4 changes the boost profile, IAT decay, and fuel trims, with no need to swap flash maps to optimize either.

The 3.5 bar map is required for > 21psi. In the JB4 we've also made the 3.5 bar map sensor the "setting" to enable the larger turbo maps. So you'll need it if you plan to run the maps shown in the dyno. Although technically speaking you could just make your own map 6 boost profile values (below 21psi) without the sensor.

The turbo stops making power over 6500rpm so I just stopped revving it up. We shift it around 6000rpm.

On the timing I found 6 degrees to be a pretty good MBT value for it. From 6-11 in 1 degree increments there is basically no gain all else being equal. Dropping below 6 started to drop power a bit. The pump map I ran on the same curve which produced the best figures but a curve of around 5 degrees would be more appropriate. We are evaluating using the same curve with a little less aggressive boost curve. Because it will simplify things for the end users if the same back end flash can be optimized for both on and off meth, allowing on the fly map changes where the JB4 changes the boost profile, IAT decay, and fuel trims, with no need to swap flash maps to optimize either.

The 3.5 bar map is required for > 21psi. In the JB4 we've also made the 3.5 bar map sensor the "setting" to enable the larger turbo maps. So you'll need it if you plan to run the maps shown in the dyno. Although technically speaking you could just make your own map 6 boost profile values (below 21psi) without the sensor.

Thanks Terry, I appreciate you sharing all this info.
Would rep again if I could.

>7/13 mfg date N55's have a different single turbo; which appears to make more power with oem parts + tunes and so one. wondering if the block, crank, rods, pistions, VANOS, etc is all the same? if so, that would help so that different / bigger turbos can yield 600+gains? At that point what would be better about the N54? VANOS alone should be a differentiation?

Thanks to all you vendors helping push the n55 forward, us owners appreciate it

@VegasJD - you are killing me bro. Where are the vidz!? left a $#@!ting comment on your latest youtube video... LOL

plz plz plz? I know you have them

lol yeah thanks i deleted them i should have reported them but i didnt i dont need negative comments on my videos, im the driver ok, my passengers are my video guys im waiting for like 4 videos of runs from last week and the ones i did today racing a 500hp mustang on e85, and 2 from the intial setup, what i dont think you realize is the tune and flash i just got yesterday, i had basic stuff and flash, it also took me over 2 months before i could even back flash my car so its been a lot longer journey to get the car there. It pulled really good in this heat tonight to almost 20lbs boost with meth

ABR - I would love to see some data backing this claim up. In a turbo application more CFM does not always equal more power. You actually lose velocity, but if the head is one of the limiting factors then you can gain HP. If the turbo is the limiting factor, then porting the head if it is already free flowing may be worthless. I haven't seen anyone else try this so getting some info out there if it is a good mod will get you more business!